Telstra's chief operating officer Brendon Riley has flagged that jobs are likely to go in a massive overhaul of the company's operating division that will affect the roles of half of all 30,170 Telstra employees.

Riley announced the changes in an email to staff at lunchtime yesterday, and seen by ZDNet.

He said that operations "must evolve" to support the company's future needs.

"We need to re-distribute our priorities, expenditure, and investment," he said in the email.

"Our traditional businesses are coming under increasing margin pressure, and the largest portion of our budget is spent supporting them. This is not a sustainable business model, and we have an obligation to redefine our contributions to Telstra."

A new operating model will be brought in as of July 1, 2013, and will see the operations division split into five groups: IT solutions, Networks, Customer Service Delivery, NBN (National Broadband Network), and NAS (Network Applications and Services). The first three are entirely new groups within Telstra.

IT solutions will be led by CIO Patrick Eltridge, networks executive director Mike Wright will head up Networks, Customer Service Delivery will be led by executive director of service delivery Phill Sporton, the NBN division will be headed up by Telstra executive director of business Greg Adcock, and the NAS division will continue to be led by David Burns.

There will also be five functional groups that work across all the divisions, including Telstra Service Operations, Assets and Facilities Management, Labour and Contract Management, Integrated Product Delivery Management, and Business Performance Management.

Riley said the majority of the media team will now join the networks team.

The exact number of positions that will go as a result of the restructure has yet to be finalised, but the change will affect over 15,000 employees. Telstra would not confirm whether estimates of hundreds of role reductions were accurate, but indicated that the full detail of the restructure would be released in the coming weeks, and would likely include job cuts.

Riley said in his email that yesterday's announcement was just the first step.

"I understand there is still a lot more work to be done to give everyone clarity around our structure throughout the organisation," he said.

"I've appointed my new leadership team, and our combined focus over the next few weeks is on helping you understand the new model, refine the structure of each group, and work out the details of the transition plans and additional proposals. While it won't be an easy process, we have a proud history of teamwork that I'm confident will help see us through."